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Diffstat (limited to 'qpid/dotnet/Qpid.Client/Client/Closeable.cs')
-rw-r--r-- | qpid/dotnet/Qpid.Client/Client/Closeable.cs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/qpid/dotnet/Qpid.Client/Client/Closeable.cs b/qpid/dotnet/Qpid.Client/Client/Closeable.cs new file mode 100644 index 0000000000..b9664ccea3 --- /dev/null +++ b/qpid/dotnet/Qpid.Client/Client/Closeable.cs @@ -0,0 +1,83 @@ +/* + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + * + */ +using System; +using Apache.Qpid.Messaging; + +namespace Apache.Qpid.Client +{ + /// <summary>Closeable provides monitoring of the state of a closeable resource; whether it is open or closed. It also provides a lock on which + /// attempts to close the resource from multiple threads can be coordinated. + /// + /// <p/><table id="crc"><caption>CRC Card</caption> + /// <tr><th> Responsibilities <th> Collaborations + /// <tr><td> Close (and clean-up) a resource. + /// <tr><td> Monitor the state of a closeable resource. + /// <tr><td> Synchronous attempts to close resource from concurrent threads. + /// </table> + /// </summary> + /// + /// <remarks>Poor encapsulation of the close lock. Better to completely hide the implementation, such that there is a method, e.g., DoSingleClose, + /// that sub-classes implement. Guaranteed to only be called by one thread at once, and iff the object is not already closed. That is, multiple + /// simultaneous closes will result in a single call to the real close method. Put the wait and condition checking loop in this base class. + /// </remarks> + public abstract class Closeable : ICloseable + { + /// <summary> Constant representing the closed state. </summary> + protected const int CLOSED = 1; + + /// <summary> Constant representing the open state. </summary> + protected const int NOT_CLOSED = 2; + + /// <summary> Used to ensure orderly closing of the object. </summary> + protected readonly object _closingLock = new object(); + + /// <summary> Indicates the state of this resource; open or closed. </summary> + protected int _closed = NOT_CLOSED; + + /// <summary> + /// Checks the not closed. + /// </summary> + /// + /// <remarks>Don't like check methods that throw exceptions. a) it can come as a surprise without checked exceptions, b) it limits the + /// callers choice, if the caller would prefer a boolean, c) it is not side-effect free programming, where such could be used. Get rid + /// of this and replace with boolean.</remarks> + protected void CheckNotClosed() + { + if (_closed == CLOSED) + { + throw new InvalidOperationException("Object " + ToString() + " has been closed"); + } + } + + /// <summary>Indicates whether this resource is closed.</summary> + /// <value><c>true</c> if closed; otherwise, <c>false</c>.</value> + public bool Closed + { + get + { + return _closed == CLOSED; + } + } + + /// <summary> Close this resource. </summary> + public abstract void Close(); + } +} |